7/29/2014 10:28 AM PDT

12:10 PM PT -- Matt Barnes tells TMZ Sports ... "We are so grateful to everyone who helped us -- from spreading the word thru social media to calling the Sacremento PD with your citizen tips."

He adds, "It was a citizen tip that led police to Michael Williams' very location late this morning. Thank you again for allowing me to be my auntie's voice and to help bring this suspect in. Also, thank you to the Sac PD!"The man suspected of murdering Matt Barnes' aunt has been CAPTURED by police in Sacramento ... and officials say it's all thanks to a concerned citizen who tipped off the cops.